1. Field of Invention
This invention relates to epoxide resin curing agents. More particularly, this invention pertains to mixed, epoxy resin based, polyamines which may be used to cure polyepoxides in aqueous systems.
2. Prior Art
Solvent based, epoxy resin curing agent systems have been known for many years. However, these solvent systems often are quite flammable and expensive and many exhibit disagreeable odors.
Moreover, in recent years increasingly strict regulation of environmental pollutants has lead to a limitation on the types and amounts of organic solvents which can be used in epoxy resin curable systems. The first approach to these limitations on the solvent content of coating systems was simply to employ a surfactant and emulsify or disperse existing polymeric systems in water. However, the cured products which resulted from these emulsions or dispersions often exhibited poor properties when compared to prior art solvent-based systems. In particular, the chemical and water resistance of such systems was often lower because of the high levels of surfactant which were needed. Therefore, the search has continued to discover epoxy resin curing agents which may be dispersed in water and which maintain the high performance levels of prior art solvent based curing agents.
U.S. Pat. No. 4,166,900 discloses cathodic electrodeposition resins prepared based upon polyepoxides, polyamines and monoepoxides. While the monoepoxides and polyamines of this patent are similar to the materials employed in this invention, the polyepoxide utilized in the '900 patent is quite different. Specifically in column 3, lines 47 to 68 there is no disclosure of the use of aliphatic, polyether based, polyepoxides in conjunction with the aromatic polyepoxide.
U.S. Pat. No. 4,246,148 discloses an aqueous coating composition based upon an epoxy polyamine adduct end capped with a monoepoxide. In this patent it is made clear that aliphatic polyether polyepoxides were not contemplated. Specifically in column 5, lines 10 to 20, a general formula is shown which clearly discloses an aromatic diepoxide, not an aliphatic polyether polyepoxide as contemplated by the inventor.
Thus it is the object of this invention to prepare epoxy resin curing agents which are useful in aqueous based systems.
It is another object of this invention to prepare water-based epoxy resins curing agents which exhibit properties equivalent to the properties of prior art solvent-based systems.
It is another object of this invention to prepare aqueous-based epoxy resin curing agents which exhibit improved compatibility with known epoxy resins systems.
It is yet another object of this invention to prepare epoxy resin curing agents having improved curing properties.
These and other objectives are obtained by preparing the epoxide resin curing agents of the instant invention.